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David I. Forrester - One of the best experts on this subject based on the ideXlab platform.
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Faster growth of Eucalyptus grandis and Eucalyptus pilularis in mixed-species stands than monocultures
Forest Ecology and Management, 2012Co-Authors: David I. Forrester, R. Geoff B. SmithAbstract:Abstract Eucalyptus plantations cover more than 20 Mha worldwide and are almost exclusively monospecific. However, in native forests Eucalyptus species often grow in mixtures. Mixed species stands of trees can be more productive than monospecific stands but despite the implications of this effect, for plantations and native Eucalyptus forests, the effects of mixing eucalypts has received little attention. The aim of this study was to examine whether two species that naturally coexist (Eucalyptus grandis W. Hill and Eucalyptus pilularis Sm.) grow faster in mixtures than their respective monocultures. Monocultures and 1:1 mixtures, and stands of two initial planting densities (1250 and 2500 trees ha−1), were used to compare the productivity and stand structures of mixtures and monocultures and to quantify inter- and intra-specific competition. Interactions between these Eucalyptus species increased their relative yields in mixtures by 10–30%. This was associated with changes in stand structure where the diameter distributions of both species became less positively skewed (lower proportions of small trees). Mixing effects were relatively consistent as the stands developed suggesting that if this complementarity effect is used in plantations there is considerable silvicultural flexibility, such that these mixed plantations could be used on both shorter rotations for biomass or pulp-logs as well as longer rotations for solid wood products. This study also suggests that interactions between co-occurring Eucalyptus species in natural forests might actually facilitate individual tree growth, in addition to simply enabling co-existence.
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mixed species plantations of Eucalyptus with nitrogen fixing trees a review
Forest Ecology and Management, 2006Co-Authors: David I. Forrester, Annette L. Cowie, Jurgen Bauhus, Jerome K VanclayAbstract:Mixed-species plantations of Eucalyptus with a nitrogen (N2) fixing species have the potential to increase productivity while maintaining soil fertility, compared to Eucalyptus monocultures. However, it is difficult to predict combinations of species and sites that will lead to these benefits. We review the processes and interactions occurring in mixed plantations, 5 and the influence of species or site attributes, to aid the selection of successful combinations of species and sites. Successful mixtures, where productivity is increased over that of monocultures, have often developed stratified canopies, such that the less shade-tolerant species overtops the more shadetolerant species. Successful mixtures also have significantly higher rates of N and P cycling than 10 Eucalyptus monocultures. It is therefore important to select N2-fixing species with readily decomposable litter and high rates of nutrient cycling, as well as high rates of N2-fixation. While the dynamics of N2-fixation in tree stands are not well understood, it appears as though eucalypts can benefit from fixed N as early as the first or second year following plantation establishment. A meta-analysis of 18 published studies revealed several trials in which mixtures were significantly 15 (P<0.001) more productive than monocultures, and no instances in which mixtures were less productive than monocultures. Regression analyses of such data were more informative than indices of relative yield, and were more informative in trials that contrasted four or more different species compositions. Thus replacement series examining compositions of 100:0, 67:33, 33:67, and 0:100 were more informative than minimalist 100:0, 50:50 and 0:100 series.
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Mixed-species plantations of Eucalyptus with nitrogen-fixing trees: A review
Forest Ecology and Management, 2006Co-Authors: David I. Forrester, Annette L. Cowie, Jurgen Bauhus, Jerome K VanclayAbstract:Mixed-species plantations of Eucalyptus with a nitrogen (N2) fixing species have the potential to increase productivity while maintaining soil fertility, compared to Eucalyptus monocultures. However, it is difficult to predict combinations of species and sites that will lead to these benefits. We review the processes and interactions occurring in mixed plantations, and the influence of species or site attributes, to aid the selection of successful combinations of species and sites. Successful mixtures, where productivity is increased over that of monocultures, have often developed stratified canopies, such that the less shade-tolerant species overtops the more shade-tolerant species. Successful mixtures also have significantly higher rates of N and P cycling than Eucalyptus monocultures. It is therefore important to select N2-fixing species with readily decomposable litter and high rates of nutrient cycling, as well as high rates of N2-fixation. While the dynamics of N2-fixation in tree stands are not well understood, it appears as though eucalypts can benefit from fixed N as early as the first or second year following plantation establishment. A meta-analysis of 18 published studies revealed several trials in which mixtures were significantly (P < 0.001) more productive than monocultures, and no instances in which mixtures were less productive than monocultures. Regression analyses of such data were more informative than indices of relative yield, and were more informative in trials that contrasted four or more different species compositions. Thus replacement series examining compositions of 100:0, 67:33, 33:67, and 0:100 were more informative than minimalist 100:0, 50:50 and 0:100 series. © 2006 Elsevier B.V. All rights reserved.
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growth dynamics in a mixed species plantation of Eucalyptus globulus and acacia mearnsii
Forest Ecology and Management, 2004Co-Authors: David I. Forrester, Jurgen Bauhus, P K KhannaAbstract:Abstract Previous work has shown greater productivity in mixed than in mono-specific stands of Eucalyptus globulus and Acacia mearnsii at age 3 and 6.5 years. To assess how long the synergistic effects of acacias on eucalypts in mixed stands would last, and what future trajectory growth might take, we investigated the growth dynamics of mixed and mono-specific plantations over the first 11 years since establishment. Monocultures of E. globulus (E) and A. mearnsii (A) and mixtures (75E:25A, 50E:50A, 25E:75A) of these species were planted following a species replacement series. At the tree level, eucalypt and acacia heights, diameters, volumes and above-ground biomass were higher in mixtures than in monocultures 3–4 years after planting. Similarly, at the stand level, volumes and above-ground biomass were significantly greater in mixtures than monocultures after 3–4 years. The difference in productivity between mixed plots and mono-specific eucalypt stands increased with time from 3 to 11 years after establishment. Litterfall was higher in the mixed stands than the monocultures, and this led to an increase in N and P cycling through litterfall in stands containing A. mearnsii. The study indicated that above-ground biomass accumulation in E. globulus plantations can be increased by acacia admixture. This can partially be explained by canopy stratification and improved nutrition of eucalypts. Although the biomass production in acacias peaked early, the synergistic effect of the acacias appears to be long lasting as was indicated by the increasing differences between mixed and pure stands.
B Dell - One of the best experts on this subject based on the ideXlab platform.
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persistence of some australian pisolithus species introduced into eucalypt plantations in china
Forest Ecology and Management, 2002Co-Authors: B Dell, N Malajczuk, W. DunstanAbstract:Some eucalypt plantations in south China grow poorly because of soil infertility and low diversity of compatible ectomycorrhizal fungi. One option to improve productivity of plantations is to introduce beneficial fungi. In order to evaluate persistence of introduced symbiotic fungi, there is a need to discriminate them from any indigenous related species. Eucalypt mycorrhizal trial sites, established for nutrition and survival studies, were used for this purpose. Seedlings of Eucalyptus camaldulensis and Eucalyptus urophylla had been inoculated with pure cultures of selected Australian ectomycorrhizal fungi, including three isolates of Pisolithus albus and one isolate each of two unnamed Pisolithus spp., and ectomycorrhizal seedlings had been out-planted at two sites in Guangzhou Province, People's Republic of China. Sequences of the internal transcribed spacers (ITSs) of ribosomal DNA (rDNA) from inoculant fungi and fungi re-isolated from sporocarps in the field were compared. Sequencing confirmed that an Australian isolate (H4111) of one unnamed Pisolithus spp. had persisted in competition with an indigenous Pisolithus spp. Selected isolates of Australian Pisolithus formed macro- and micro-morphologically typical ectomycorrhizas in pure culture syntheses and in the field. In comparison, the indigenous Chinese Pisolithus formed an incomplete association with a poorly developed mantle. Comparisons between ITS sequences from Pisolithus isolates associated with Eucalyptus spp. from elsewhere in the world and ITS sequences of Australian Pisolithus spp. indicate that the same unnamed Pisolithus spp. has also become established in Portugal, Brazil and South Africa. Because Pisolithus isolate H4111 produced sporocarps in south China under eucalypts and promoted tree growth, this fungus would be useful in spore orchards to provide spore inoculum for eucalypt nurseries. The local Chinese Pisolithus is not recommended for inoculation programs because it is ineffective in forming mycorrhizas with eucalypts. The isolate H4111 is from a Pisolithus that occurs naturally along the east coast of Australia. Although this Pisolithus has been widely dispersed with eucalypts in other parts of the world, it is not present in eucalypt plantations in east Asia.
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Boron requirements for Eucalyptus globulus seedlings
Plant and Soil, 2002Co-Authors: A.t. Sakya, B Dell, L. HuangAbstract:Although boron (B) deficiency limits the productivity of eucalypts in plantations in many parts of the world, the concentrations of foliar B used in the diagnosis of B deficiency vary greatly among studies. There has been a lack of reliable diagnosis standards for B deficiency in Eucalyptus species. Therefore, the present study investigated the relationship between internal and external B concentrations and growth of Eucalyptus globulus , the main commercial temperate eucalypt species. Seedlings were grown in a B-buffered solution culture (Amberlite IRA 743) from 0.03 to 8.35 μ M B. Boron deficiency symptoms appeared at day 5 in the nutrient solution containing less than 0.27 μ M B. The external critical B concentrations, estimated for the growth of shoots and roots, were 1.08 and 0.99 μ M B, respectively. The internal critical B concentration range in the youngest fully expanded leaf (YFEL) for shoot growth was 12–16 mg B kg^−1 dry weight. The internal critical B concentrations estimated in the present study have been successfully used in the diagnosis of B deficiency in E. globulus trees up to three years of age in south-east Asia.
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Field performance of Eucalyptus urophylla inoculated with an introduced and idigenous strains of Pisolithus at three sites in the Philippines
1998Co-Authors: Nelly S. Aggangan, B Dell, N Malajczuk, L. DeAbstract:The effectiveness of an isolate of Pisolithus from Australia was compared with a Philippine Pisolithus isolate in promoting the growth of Eucalyptus urophylla on three acid (pH 4.1-5.9, 0.005M CaCl2) sites in the Philippines (Pangasinan, Bukidnon and Surigao). Isolates of Pisolithus were taken from basidiocarps collected under eucalypts growing in Western Australia and from the Philippines. Generally, the introduced Pisolithus promoted greater wood volume of E. urophylla planted in dry marginal land (Pangasinan) and in moist logged-over area (Surigao) in the Philippines than the Philippine Pisolithus isolate. Root colonization by the two fungi did not vary but there was a difference in the root colonization levels between sites implying that the prevailing microclimatic conditions on each site had affected the performance of the ECM inoculants. In this study, the number of isolates tested was limited, thus, future field trials should include a wider range of ectomycorrhizal fungi. Further work is required to determine whether the growth responses measured at the two sites (Pangasinan and Surigao) are maintained until the trees are harvested.
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Persistence of Australian Pisolithus species in eucalypt plantations in China
1996Co-Authors: N Malajczuk, B Dell, Treena I. BurgessAbstract:Persistence of Australian Pisolithus species in eucalypt plantations in China The persistence of Australian Pisolithus isolates introduced into experimental plantations of eucalypts in southern China was examined by recording the presence of sporocarps one to four years after planting. Electrophoretic patterns of polypeptides extracted from mycelial cultures obtained from Pisolithus sporocarps confirmed the successful colonization of eucalypt seedlings in southern China. Although the indigenous Chinese Pisolithus was present in the eucalypt plantations, it appears to be a poor coloniser of eucalypt roots and failed to form functionally mature ectomycorrhizal structures in vitro. The pattern of basidiocarp abundance in the field suggests that the Australian Pisolithus isolates out-competed the indigenous Pisolithus in Eucalyptus plantations in China once successful inoculation of seedlings is achieved in the nursery.
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Soil fumigation and phosphorus supply affect the formation of Pisolithus-Eucalyptus urophylla ectomycorrhizas in two acid Philippine soils
Plant and Soil, 1996Co-Authors: Nelly S. Aggangan, B Dell, N Malajczuk, R. De La CruzAbstract:To examine the effects of microbial populations and external phosphorus supply of two Philippine soils on mycorrhizal formation, Eucalyptus urophylla seedlings were inoculated with two Pisolithus isolates and grown in fumigated, reinfested and unfumigated soil fertilized with four rates of phosphorus. The Pisolithus isolates used were collected from under eucalypts in Australia and in the Philippines. Soils were infertile acid silty loams collected from field sites in Pangasinan, Luzon and Surigao, Mindanao.
Jurgen Bauhus - One of the best experts on this subject based on the ideXlab platform.
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mixed species plantations of Eucalyptus with nitrogen fixing trees a review
Forest Ecology and Management, 2006Co-Authors: David I. Forrester, Annette L. Cowie, Jurgen Bauhus, Jerome K VanclayAbstract:Mixed-species plantations of Eucalyptus with a nitrogen (N2) fixing species have the potential to increase productivity while maintaining soil fertility, compared to Eucalyptus monocultures. However, it is difficult to predict combinations of species and sites that will lead to these benefits. We review the processes and interactions occurring in mixed plantations, 5 and the influence of species or site attributes, to aid the selection of successful combinations of species and sites. Successful mixtures, where productivity is increased over that of monocultures, have often developed stratified canopies, such that the less shade-tolerant species overtops the more shadetolerant species. Successful mixtures also have significantly higher rates of N and P cycling than 10 Eucalyptus monocultures. It is therefore important to select N2-fixing species with readily decomposable litter and high rates of nutrient cycling, as well as high rates of N2-fixation. While the dynamics of N2-fixation in tree stands are not well understood, it appears as though eucalypts can benefit from fixed N as early as the first or second year following plantation establishment. A meta-analysis of 18 published studies revealed several trials in which mixtures were significantly 15 (P<0.001) more productive than monocultures, and no instances in which mixtures were less productive than monocultures. Regression analyses of such data were more informative than indices of relative yield, and were more informative in trials that contrasted four or more different species compositions. Thus replacement series examining compositions of 100:0, 67:33, 33:67, and 0:100 were more informative than minimalist 100:0, 50:50 and 0:100 series.
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Mixed-species plantations of Eucalyptus with nitrogen-fixing trees: A review
Forest Ecology and Management, 2006Co-Authors: David I. Forrester, Annette L. Cowie, Jurgen Bauhus, Jerome K VanclayAbstract:Mixed-species plantations of Eucalyptus with a nitrogen (N2) fixing species have the potential to increase productivity while maintaining soil fertility, compared to Eucalyptus monocultures. However, it is difficult to predict combinations of species and sites that will lead to these benefits. We review the processes and interactions occurring in mixed plantations, and the influence of species or site attributes, to aid the selection of successful combinations of species and sites. Successful mixtures, where productivity is increased over that of monocultures, have often developed stratified canopies, such that the less shade-tolerant species overtops the more shade-tolerant species. Successful mixtures also have significantly higher rates of N and P cycling than Eucalyptus monocultures. It is therefore important to select N2-fixing species with readily decomposable litter and high rates of nutrient cycling, as well as high rates of N2-fixation. While the dynamics of N2-fixation in tree stands are not well understood, it appears as though eucalypts can benefit from fixed N as early as the first or second year following plantation establishment. A meta-analysis of 18 published studies revealed several trials in which mixtures were significantly (P < 0.001) more productive than monocultures, and no instances in which mixtures were less productive than monocultures. Regression analyses of such data were more informative than indices of relative yield, and were more informative in trials that contrasted four or more different species compositions. Thus replacement series examining compositions of 100:0, 67:33, 33:67, and 0:100 were more informative than minimalist 100:0, 50:50 and 0:100 series. © 2006 Elsevier B.V. All rights reserved.
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growth dynamics in a mixed species plantation of Eucalyptus globulus and acacia mearnsii
Forest Ecology and Management, 2004Co-Authors: David I. Forrester, Jurgen Bauhus, P K KhannaAbstract:Abstract Previous work has shown greater productivity in mixed than in mono-specific stands of Eucalyptus globulus and Acacia mearnsii at age 3 and 6.5 years. To assess how long the synergistic effects of acacias on eucalypts in mixed stands would last, and what future trajectory growth might take, we investigated the growth dynamics of mixed and mono-specific plantations over the first 11 years since establishment. Monocultures of E. globulus (E) and A. mearnsii (A) and mixtures (75E:25A, 50E:50A, 25E:75A) of these species were planted following a species replacement series. At the tree level, eucalypt and acacia heights, diameters, volumes and above-ground biomass were higher in mixtures than in monocultures 3–4 years after planting. Similarly, at the stand level, volumes and above-ground biomass were significantly greater in mixtures than monocultures after 3–4 years. The difference in productivity between mixed plots and mono-specific eucalypt stands increased with time from 3 to 11 years after establishment. Litterfall was higher in the mixed stands than the monocultures, and this led to an increase in N and P cycling through litterfall in stands containing A. mearnsii. The study indicated that above-ground biomass accumulation in E. globulus plantations can be increased by acacia admixture. This can partially be explained by canopy stratification and improved nutrition of eucalypts. Although the biomass production in acacias peaked early, the synergistic effect of the acacias appears to be long lasting as was indicated by the increasing differences between mixed and pure stands.
N Malajczuk - One of the best experts on this subject based on the ideXlab platform.
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persistence of some australian pisolithus species introduced into eucalypt plantations in china
Forest Ecology and Management, 2002Co-Authors: B Dell, N Malajczuk, W. DunstanAbstract:Some eucalypt plantations in south China grow poorly because of soil infertility and low diversity of compatible ectomycorrhizal fungi. One option to improve productivity of plantations is to introduce beneficial fungi. In order to evaluate persistence of introduced symbiotic fungi, there is a need to discriminate them from any indigenous related species. Eucalypt mycorrhizal trial sites, established for nutrition and survival studies, were used for this purpose. Seedlings of Eucalyptus camaldulensis and Eucalyptus urophylla had been inoculated with pure cultures of selected Australian ectomycorrhizal fungi, including three isolates of Pisolithus albus and one isolate each of two unnamed Pisolithus spp., and ectomycorrhizal seedlings had been out-planted at two sites in Guangzhou Province, People's Republic of China. Sequences of the internal transcribed spacers (ITSs) of ribosomal DNA (rDNA) from inoculant fungi and fungi re-isolated from sporocarps in the field were compared. Sequencing confirmed that an Australian isolate (H4111) of one unnamed Pisolithus spp. had persisted in competition with an indigenous Pisolithus spp. Selected isolates of Australian Pisolithus formed macro- and micro-morphologically typical ectomycorrhizas in pure culture syntheses and in the field. In comparison, the indigenous Chinese Pisolithus formed an incomplete association with a poorly developed mantle. Comparisons between ITS sequences from Pisolithus isolates associated with Eucalyptus spp. from elsewhere in the world and ITS sequences of Australian Pisolithus spp. indicate that the same unnamed Pisolithus spp. has also become established in Portugal, Brazil and South Africa. Because Pisolithus isolate H4111 produced sporocarps in south China under eucalypts and promoted tree growth, this fungus would be useful in spore orchards to provide spore inoculum for eucalypt nurseries. The local Chinese Pisolithus is not recommended for inoculation programs because it is ineffective in forming mycorrhizas with eucalypts. The isolate H4111 is from a Pisolithus that occurs naturally along the east coast of Australia. Although this Pisolithus has been widely dispersed with eucalypts in other parts of the world, it is not present in eucalypt plantations in east Asia.
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Field performance of Eucalyptus urophylla inoculated with an introduced and idigenous strains of Pisolithus at three sites in the Philippines
1998Co-Authors: Nelly S. Aggangan, B Dell, N Malajczuk, L. DeAbstract:The effectiveness of an isolate of Pisolithus from Australia was compared with a Philippine Pisolithus isolate in promoting the growth of Eucalyptus urophylla on three acid (pH 4.1-5.9, 0.005M CaCl2) sites in the Philippines (Pangasinan, Bukidnon and Surigao). Isolates of Pisolithus were taken from basidiocarps collected under eucalypts growing in Western Australia and from the Philippines. Generally, the introduced Pisolithus promoted greater wood volume of E. urophylla planted in dry marginal land (Pangasinan) and in moist logged-over area (Surigao) in the Philippines than the Philippine Pisolithus isolate. Root colonization by the two fungi did not vary but there was a difference in the root colonization levels between sites implying that the prevailing microclimatic conditions on each site had affected the performance of the ECM inoculants. In this study, the number of isolates tested was limited, thus, future field trials should include a wider range of ectomycorrhizal fungi. Further work is required to determine whether the growth responses measured at the two sites (Pangasinan and Surigao) are maintained until the trees are harvested.
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Persistence of Australian Pisolithus species in eucalypt plantations in China
1996Co-Authors: N Malajczuk, B Dell, Treena I. BurgessAbstract:Persistence of Australian Pisolithus species in eucalypt plantations in China The persistence of Australian Pisolithus isolates introduced into experimental plantations of eucalypts in southern China was examined by recording the presence of sporocarps one to four years after planting. Electrophoretic patterns of polypeptides extracted from mycelial cultures obtained from Pisolithus sporocarps confirmed the successful colonization of eucalypt seedlings in southern China. Although the indigenous Chinese Pisolithus was present in the eucalypt plantations, it appears to be a poor coloniser of eucalypt roots and failed to form functionally mature ectomycorrhizal structures in vitro. The pattern of basidiocarp abundance in the field suggests that the Australian Pisolithus isolates out-competed the indigenous Pisolithus in Eucalyptus plantations in China once successful inoculation of seedlings is achieved in the nursery.
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Soil fumigation and phosphorus supply affect the formation of Pisolithus-Eucalyptus urophylla ectomycorrhizas in two acid Philippine soils
Plant and Soil, 1996Co-Authors: Nelly S. Aggangan, B Dell, N Malajczuk, R. De La CruzAbstract:To examine the effects of microbial populations and external phosphorus supply of two Philippine soils on mycorrhizal formation, Eucalyptus urophylla seedlings were inoculated with two Pisolithus isolates and grown in fumigated, reinfested and unfumigated soil fertilized with four rates of phosphorus. The Pisolithus isolates used were collected from under eucalypts in Australia and in the Philippines. Soils were infertile acid silty loams collected from field sites in Pangasinan, Luzon and Surigao, Mindanao.
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development and function of pisolithus and scleroderma ectomycorrhizas formed in vivo with allocasuarina casuarina and Eucalyptus
Mycorrhiza, 1994Co-Authors: B Dell, Neale L. Bougher, N Malajczuk, G ThomsonAbstract:The effect of inoculating seedlings of Eucalyptus grandis, Allocasuarina littoralis and Casuarina equisetifolia with two isolates of Pisolithus and two isolates of Scleroderma from under eucalypts was examined in a glasshouse trial. Ectomycorrhizas formed extensively on Eucalyptus (23–46% fine roots ectomycorrhizal) and Allocasuarina (18–51% fine roots ectomycorrhizal). On Casuarina, the fungi were either unable to colonize the rhizosphere (one isolate of Pisolithus), or sheathed roots, resembling ectomycorrhizas, formed on 1–2% of the fine roots. Colonization of roots by one isolate of Scleroderma resulted in the death of Casuarina seedlings. Inoculation with fungi increased shoot dry weight by up to a factor of 32 (Eucalyptus), 4 (Allocasuarina) and 3 (Casuarina). Ectomycorrhizas formed in associations with Eucalyptus and Allocasuarina had fully differentiated mantles and Hartig nets in which the host and fungal cells were linked by an extensive fibrillar matrix. Sheathed roots in Casuarina lacked a Hartig net, and the epidermis showed a hypersensitive reaction resulting in wall thickening and cell death. The sheaths are described as mantles since the density and arrangement of the hyphae in the sheaths was similar to that in mantles of the eucalypt ectomycorrhizas. The intercellular carbohydrate matrix was not produced in the Casuarina mantle in association with Pisolithus, hence the mantle was not cemented to the root. These structures differ from poorly compatible associations described previously for Pisolithus and Eucalyptus. The anatomical data indicate that ectomycorrhizal assessment based on surface morphological features may be misleading in ecological studies because compatible and incompatible associations may not be distinguishable.
Jerome K Vanclay - One of the best experts on this subject based on the ideXlab platform.
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mixed species plantations of Eucalyptus with nitrogen fixing trees a review
Forest Ecology and Management, 2006Co-Authors: David I. Forrester, Annette L. Cowie, Jurgen Bauhus, Jerome K VanclayAbstract:Mixed-species plantations of Eucalyptus with a nitrogen (N2) fixing species have the potential to increase productivity while maintaining soil fertility, compared to Eucalyptus monocultures. However, it is difficult to predict combinations of species and sites that will lead to these benefits. We review the processes and interactions occurring in mixed plantations, 5 and the influence of species or site attributes, to aid the selection of successful combinations of species and sites. Successful mixtures, where productivity is increased over that of monocultures, have often developed stratified canopies, such that the less shade-tolerant species overtops the more shadetolerant species. Successful mixtures also have significantly higher rates of N and P cycling than 10 Eucalyptus monocultures. It is therefore important to select N2-fixing species with readily decomposable litter and high rates of nutrient cycling, as well as high rates of N2-fixation. While the dynamics of N2-fixation in tree stands are not well understood, it appears as though eucalypts can benefit from fixed N as early as the first or second year following plantation establishment. A meta-analysis of 18 published studies revealed several trials in which mixtures were significantly 15 (P<0.001) more productive than monocultures, and no instances in which mixtures were less productive than monocultures. Regression analyses of such data were more informative than indices of relative yield, and were more informative in trials that contrasted four or more different species compositions. Thus replacement series examining compositions of 100:0, 67:33, 33:67, and 0:100 were more informative than minimalist 100:0, 50:50 and 0:100 series.
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Mixed-species plantations of Eucalyptus with nitrogen-fixing trees: A review
Forest Ecology and Management, 2006Co-Authors: David I. Forrester, Annette L. Cowie, Jurgen Bauhus, Jerome K VanclayAbstract:Mixed-species plantations of Eucalyptus with a nitrogen (N2) fixing species have the potential to increase productivity while maintaining soil fertility, compared to Eucalyptus monocultures. However, it is difficult to predict combinations of species and sites that will lead to these benefits. We review the processes and interactions occurring in mixed plantations, and the influence of species or site attributes, to aid the selection of successful combinations of species and sites. Successful mixtures, where productivity is increased over that of monocultures, have often developed stratified canopies, such that the less shade-tolerant species overtops the more shade-tolerant species. Successful mixtures also have significantly higher rates of N and P cycling than Eucalyptus monocultures. It is therefore important to select N2-fixing species with readily decomposable litter and high rates of nutrient cycling, as well as high rates of N2-fixation. While the dynamics of N2-fixation in tree stands are not well understood, it appears as though eucalypts can benefit from fixed N as early as the first or second year following plantation establishment. A meta-analysis of 18 published studies revealed several trials in which mixtures were significantly (P < 0.001) more productive than monocultures, and no instances in which mixtures were less productive than monocultures. Regression analyses of such data were more informative than indices of relative yield, and were more informative in trials that contrasted four or more different species compositions. Thus replacement series examining compositions of 100:0, 67:33, 33:67, and 0:100 were more informative than minimalist 100:0, 50:50 and 0:100 series. © 2006 Elsevier B.V. All rights reserved.
